In many situations the entry of data is of a "non-critical" nature. Such situations would be where a deliberate alteration or forgery would not result in any unlawful gain. In such non-critical situations, as in the printing of ledger statements for use within a company, or other similar situations, the normal entry of data on a medium such as paper would be "black on white" or any suitable contrasting color combination. However, in critical situations, double entry of data on the same instrument is commonly made in an attempt to prevent forgery on for example, checks or other negotiable instruments. Commonly the dollar amount a check is payable for is entered twice, sometimes both entries use arabic numerals, or one entry is in arabic numerals while the other is in words. Regardless of the precautions taken the ingenious forger is sometimes able to alter such data sufficiently to obtain an illegal gain.